For example, in an information recording medium, such as a CD-ROM (Compact Disc-Read Only Memory), a CD-R (Compact Disc-Recordable), and a DVD-ROM, there are developed a multiple layer or multilayer type, or double layer (or dual layer or two-layer) type optical disc and so on, in which a plurality of recording layers are laminated on the same substrate. More specifically, the two-layer type optical disc has a first recording layer (referred to as a “L0 layer” in this application), as the first layer, which is located on the front (i.e. a side closer to an optical pickup) as viewed from a laser light emission side in recording information on the information recording apparatus, and further has a semi-transparent reflective coating or film, located on the rear thereof (i.e. a side farther from the optical pickup). As the second recording layer, it has a second recording layer (referred to as a “L1 layer” in this application), located on the rear of the semitransparent reflective coating through a middle layer, such as an adhesive layer, and further has a reflective film located on the rear thereof. In preparing such a multilayer type information recording medium, the L0 layer and the L1 layer are individually formed and pasted in the end, to thereby prepare the two-layer type optical disc at a low cost.
In the information recording apparatus, such as a CD recorder, for recording information onto such a two-layer type optical disc, the information is recorded into the L0 layer in a rewritable method or irreversible change recording method by irreversible change recording heat by using heat or the like, by focusing the laser light for recording onto the L0 layer, and the information is recorded into the L1 layer in a rewritable method or irreversible change recording method by heat or the like, by focusing the laser light onto the L1 layer.
Patent document 1: Japanese Patent Application Laid Open NO. 2002-352469